Field of the Disclosure
Embodiments disclosed herein relate generally to the production of high purity alpha-olefins, such as C4 to C8 olefins, for use in various downstream processes, such as use as a co-monomer in the production of polyethylenes and polypropylenes, among other end uses. More specifically, embodiments disclosed herein relate to the more efficient production and purification of alpha-olefins utilizing isomerization and metathesis.
Background
Processes for producing high purity polymer-grade comonomers include various 1-butene comonomer production processes and 1-hexene comonomer production processes. These processes utilize metathesis and/or double-bond isomerization reactions that occur over specific catalysts using mixed n-butenes as the feed to produce polymer-grade 1-butene and 1-hexene used as comonomers for production of polyethylene. However, these processes are extremely energy intensive as they employ distillation to separate the desired alpha-olefin (1-butene and 1-hexene) with high purity from mixtures of their positional isomers that exhibit very close boiling points (2-butene and 2-hexene, 3-hexene, respectively).
For example, the 1-butene process flow includes a butenes superfractionator that separates the 1-butene product from 2-butene. The 1-hexene process is even more energy intensive as it requires two superfractionators: a butenes superfractionator to separate a high-purity 1-butene stream used to produce hexenes, and a hexenes superfractionator to separate the final 1-hexene product from the other positional hexene isomers (2-hexene and 3-hexene).
The high operating costs associated with the energy intensive distillation towers in the processes render them economically less attractive, especially for the 1-hexene process that requires two (2) superfractionators. Similar processes for production of 1-octene would be even more separation intensive, separating 1-octene from a mixture of 2-, 3-, and 4-octene.